public class Demo2 {
    private static int count;
    public static void main(String[] args) throws InterruptedException {
        Object locker = new Object();

        Thread t1 = new Thread(()->{
            synchronized (locker){
                for(int i = 0;i < 10000;i++){
                    count++;
                }
            }
        });

        Thread t2 = new Thread(()->{
           synchronized (locker){
               for(int i = 0;i < 10000;i++){
                   count++;
               }
           }
        });

        t1.start();
        t2.start();

        t1.join();
        t2.join();

        System.out.println("count = " + count);
    }
}
